Mixing apparatus

ABSTRACT

This invention relates to apparatus for continuously mixing dry bulk material with a liquid to form a slurry. The apparatus provides for the dry material to be added to the liquid for initial wetting of the dry material. The wetted material is then directed against a baffle from which it is deflected into a reservoir. The slurry thus formed is circulated by a suitable pump from the reservoir through a system of piping back into a shroud enveloping the initial wetting device, and is discharged with a rotary motion back into the reservoir. Centrifugal force resulting from rotary motion of the slurry prevents material from splashing back into the dry material delivery tube. In the initial wetting stage of the system, the liquid is formed into a hollow cylindrical pattern within and more or less concentric with the circulating slurry which has also been shaped into a hollow cylindrical pattern, revolving helically as it exits into the reservoir. The dry material is introduced into the hollow center of the liquid cylinder, and therefore must pass through the liquid before exiting into the reservoir.

D United States Patent [1 1 {111 3,741,533 Winn, Jr. June 26, 1973MIXING APPARATUS [57] ABSTRACT [75] Inventor: Fred Winn Tulsa Okla- Thisinvention relates to apparatus for continuously 7 3 Assignee; T Dow C iCompany, mixing dry bulk material with a liquid to form a slurry.Midland, Mi The apparatus provides for the dry material to be added tothe liquid for initial wetting of the dry mate- [22] Flled: 1971 rial.The wetted material is then directed against a baf- [21 1 App]. 139,247fle from which it is deflected into a reservoir. The slurry thus formedis circulated by a suitable pump from the reservoir through a system ofpiping back into a shroud [52] U.S. Cl. 259/4, 259/168 enveloping theinitial wetting device, and discharged [51] Ilit. Cl. B0 5/12, BOlf15/02 with a rotary motion b i the reservoir Centrifw [58] w of sgarch259/4 gal force resulting from rotary motion of the slurry pre- 259/162,164, 165, 168, 146, 148, 151, 147 vents material from splashing backinto the dry mate-' [56] R f C1 d rial delivery tube.

e erences I e In the initial wetting stage of the system, the liquid isT D STATES PATENTS formed into a hollow cylindrical pattern within and1,680,678 8/1928 Halliburton 259/147 more or l ntri with the circulatingslurry 2,523,514 11/1950 HafVey 259/4 which has also been shaped into ahollow cylindrical I P ttern, revolving helically as it exits into thereservoir. 3484082 12/1969 The dry material is introduced mto the hollowcenter Dupeuble 259/153 Primary Exa n'tinen-l lobert W. Jenkins Attomey- William. M. Yates and Earl D. Ayers of the liquid cylinder, andtherefore must pass through the liquid before exiting into thereservoir.

6 Claims, 4 Drawing Figures Liquid .2

r 6.56/- vo/r BACKGROUND OF THE INVENTION This invention relates toapparatus for mixing particulate solid material with a liquid containingmedium, and particularly to cement mixing apparatus.

In oil and gas well (or other earth well) cementing service, it isnecessary to provide cement mixers which will rapidly prepare largequantities of neat cement at a predetermined density. The neat cement isthen pumped into the well being treated.

Paddle type mixers and so-called jet-mixers are commonly used inpreparing neat cement for use in well cementing service. Paddle typemixers do an excellent job of mixing but require a mixing tank having arelatively large volume. Since the tank and mixer must be transportedfrom well to well, the bulk and weight make this type of mixingequipment somewhat expensive to use as compared to lighter, less bulkyequipment. Further, when thick slurries are mixed, the equipmentoperator must be careful not to permit the paddles to stick. Inaddition, cleanup of the equipment after use can be a practical problemwhen this type of mixer is used.

Jet type mixers function well in making ordinary cement slurries, butthe adequate mixing of gel cements has proven difficult with a jet typemixer. Also, the jet mixer usually requires the use of one of thetreating pumps to drive the jet, decreasing the capacity of the treatingtruck of actuallypump cement into the well.

Recently vortex mixers of the type disclosed and claimed in U. S. Pat.No. 3,201,093 have been used. While such mixtures are adequate for manyuses, extremely dense slurries are difficult to make with such devices.

OBJECTS OF THE INVENTION Accordingly, a principal object of thisinvention is to provide an improved mixing apparatus.

Another object of this invention is to provide an improved mixingapparatus which requires a relatively small amount of energy to operateit as compared with .prior art devices for making dense slurries.

A further object of this invention is to provide a lighter, more compactapparatus for use in making dense slurries.

STATEMENT OF THEINVENTION In accordance with this invention, there isprovided apparatus to continuously mix dry bulk material with a liquidto form a slurry. The apparatus provides for the dry material to beadded to the liquid for initial wetting of the dry material. The wettedmaterial is then directed against a baffle (which may be the bottom ofthe reservoir) from which it is deflected into the reservoir.

more or less concentric with the circulating slurry which has also beenshaped into a hollow cylindrical pattern, revolving helieally as itexits into the reservoir. The dry material is introduced into the hollowcenter of the liquid cylinder, and therefore must pass through theliquid before exiting into the reservoir.

The liquid may be introduced tangentially or radially. In any event, theliquid should exit at the lower end of the annular jacket in suchfashion as to not splash back into the dry material conduit where cakingmight occur.

BRIEF DESCRIPTION OF THE DRAWING The invention, as well as additionalobjects and advantages thereof, will best be understood when thefollowing detailed description is read in connection with theaccompanying drawing, in which:

FIG. 1 is a simplified diagrammatical view, partly in section, of mixingapparatus in accordance with this invention;

FIG. 2 is a plan view of FIG. 1;

FIG. 3 is a simplified diagrammatical view, partly in section, of analternative embodiment ofthis invention, and

FIG. 4 is a plan view of FIG. 3.

DETAILED DESCRIPTION OF THE DRAWING Referring to the drawings, andparticularly to FIGS. 1 and 2, there is shown mixing apparatus,indicated generally by the numeral 10, a slurry reservoir 12 into whichthe apparatus 10 extends, and associated piping and pumping means.

The apparatus 10 includes a central dry mix inlet tube 14, usuallyvertically disposed, surrounded along its lower part by a concentrictubular part 16 (middle tubular part) which communicates at its upperend with a cylindrically shaped hollow member 18 whose top is sealedaround the tube 14 and whose bottom is sealed at its inner edges to theupper end of the tubular part 16. A liquid inlet tube is coupledtangentially through the side wall of the hollow member 18.

A third or outer tubular element 24 concentrically surrounds and isspaced from the lower part of the tubular part 16.

Another member 22, of substantially larger diameter than the diameter ofthe tubular element 24 and having a top, bottom, and curved side wallssurrounds the tubular part 16 below the hollow member 18. The top of themember 22 is sealed to the wall of the tubular part 16 while the bottomthereof is sealed to the top of the tubular element 24.

A slurry inlet line 26 communicates tangentially with the interior ofthe member 22.

A liquid reservoir 50 is coupled through line 52, pump 54 and valve 56to the'liquid inlet tube 20.

Slurry from the reservoir or tank 12 is recirculated by means of line34, pump 36, line 38, valve 40 and line 42 to the slurry inlet 22.

In operation, liquid, water plus additives, for example, is pumped fromthe reservoir 50 to the hollow member 18 through the inlet '20, swirlingaround the cylindrical chamber walls and exiting downwardly along thewalls of the tubular part 16. Dry cement or other particulated materialenters the apparatus from above via the'inlet tube 14. The inlet tube 14may be coupled to a metering hopper (not shown) into which cement may beloaded or to a pneumatically operated cement distribution line (notshown).

Usually some liquid is introduced into the reservoir 12 via the tube'l6before the cement and/or other particulated material is added. Theliquid enters the chamber defined by the hollow member 18 at sufficientpressure to produce a swirling vortex therein, the swirling liquid whichcannot be contained in the chamber being dispersed downwardly inswirling sheet like form along the inner wall of the tube 16, impingingon the bottom of the reservoir (or upon a baffle plate if the bottom ofthe reservoir is an excessive distance from the bottom 30 of the tube16).

The particulated material enters the apparatus and passes down the tube14 to its bottom 28 whereupon it is urged outwardly and downwardly tocontact the liquid which is escaping from the end 30 of the tube 16. Theviolent shearing action as the liquid emerges from the annulus betweenthe tube 16 and the tube 14 hits the baffle plate or bottom of thereservoir results in turbulance which causes intimate mixing of thecement with the water at a rapid rate.

The inventory of the reservoir 12 is then pumped via line 34, pump 36line 38, valve 40 and line 42 through the slurry inlet line 26 to thevortex forming chamber defined by the member 22 where it is forceddownwardly through the annulus between the tube 16 and the tubularelement 24.

The particulated materials and liquid, mixed or unmixed, then combineswith and is intimately mixed with the already mixed slurry enteringthrough the inlet 26. In order to increase the slurry density the amountof liquid introduced through the inlet is substantially reduced withrespect to the amount of particulated material entering the tube 14.

Because of the continuing recirculation of the inventory of thereservoir 12 as the density of the slurry is being increased, a moreuniform density is achieved in the material in the reservoir.

After the required slurry density is reached, valve 46 is opened and thedense slurry is pumped to the well or other utilization point withrecirculation continuing at a reduced rate. Often a booster pump 48 isused to inject the cement into the well.

The embodiment of the apparatus shown in FIGS. 3 and 4 is in most casessimilar to that shown in FIGS. 1 and 2. The reservoir 60, hollow member66, chamber member 70, slurry inlet tube 74 and tubular element 72 arethe same as reservoir 12, hollow member 18, member 22, slurry inlet 26and tubular element 24, respectively. inlet tube 62, though similar totube 14, is substantially shorter than tube 14, its lower end 76 beingjust below the lower end 78 of tube 64 (which other than for its shorterlength corresponds to the tube 30). The lower end of the tube 76 is justbelow the bottom of the slurry reentry member 70. The liquid inlet 68 isconnected to the member 66 radially.

In the operation of the apparatus of FIGS. 3 and 4, the liquid extendsdown the annulus between the tubular elements 62, 64 in a sheet-likemanner adjacent to and within the sheath of recirculated slurry whichdescends from the slurry recirculation chamber defined by the member 70.The particulated material entering through the tube 62 disperses andcontacts the sheetlike liquid and is wet by that liquid beforecontacting the recirculating slurry and being mixed with it as thematerials are deflected in a turbulent manner from the bottom of thereservoir 60 or other baffle plate.

In one test, the mixer, of the type shown in FIGS. 1

and 2, mixed a slurry having a density of 19.5 pounds per gallon at arate in excess of 2 barrels per minute. The particulated materialcomprised alamo Class H cement, silica sand.

It appears that the mixing of the dry particulated material with aliquid before it is mixed with the recirculated slurry results inimproved initial wetting of the particulated material and in better,faster mixing than occurred in prior art type mixers. Further, usingseparate liquid entry and recirculated slurry entry chambers makes iteasier to control the relative amounts introduced to the apparatus thanif a common entry chamber was used.

What is claimed is:

1. Slurry mixing apparatus comprising a liquid entry chamber having atop, a bottom, and a generally circular inner peripheral wall, liquidinlet means communicating with said wall, a particulated material inlettube, said tube being smaller in diameter than the diameter of saidliquid entry chamber and extending concentrically through the top andbottom and substantially below the bottom of said liquid entry chamberand sealed to said top,

a liquid outlet tube, said liquid outlet tube surrounding and beingspaced from said particulated material inlet tube and being sealed tothe bottom of said liquid entry chamber, a recirculated slurry entrychamber having a top, a bottom and a generally circular inner peripheralwall, said particulated material inlet tube and liquid outlet tubeextending through said recirculated slurry entry chamber, said liquidoutlet tube being sealed to the top of said slurry entry chamber, meansfor introducing slurry through said wall of said slurry entry chamber, arecirculated slurry outlet tube, said recirculated slurry outlet tubesurrounding and being spaced from said liquid outlet tube and beingsealed to said bottom of said slurry entry chamber, said slurry outlettube extending at least to the bottom of said liquid outlet tube andsaid particulated materials inlet tube, baffle means below said slurryoutlet tube, a reservoir having walls extending above the bottom of saidslurry outlet tube, and means for recirculating slurry from saidreservoir to said means for introducing slurry.

2. Apparatus in accordance with claim 1, wherein said liquid inlet meansis a tangentially disposed tube.

3. Apparatus in accordance with claim 1, wherein said means forintroducing recirculated slurry is disposed generally tangentially withrespect to the wall of said slurry entry chamber.

4. Apparatus in accordance with claim 1, wherein said particulatedmaterial inlet tube, said liquid outlet tube and said recirculatedslurry outlet tube are coaxial with respect to each other.

5. Apparatus in accordance with claim 1, wherein said recirculatedslurry outlet tube extends substantially below said liquid outlet tubeand said particulated material inlet tube.

6. Apparatus in accordance with claim 1, wherein means are provided forapplying liquid under substantial pressure to said liquid inlet means.

UNITED STATES PATENT. OFFICE CERTIFICATE OF CORRECTION Patent No. 2 7 1533 Dated June 26 1973 Inventor(s) Fred M. Winn, Jr. and Omer E.Carrington It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

Page 1, after "Inventorz" add the following name "Omer E. Carrington'Signed and sealed this th-day of August, 197

(SEAL) Attest:

MCCOY M' GIBSON; JR? 0. MARSHALL DANN Attestlng Officer Commissioner ofPatents

1. Slurry mixing apparatus comprising a liquid entry chamber having atop, a bottom, and a generally circular inner peripheral wall, liquidinlet means communicating with said wall, a particulated material inlettube, said tube being smaller in diameter than the diameter of saidliquid entry chamber and extending concentrically through the top andbottom and substantially below the bottom of said liquid entry chamberand sealed to said top, a liquid outlet tube, said liquid outlet tubesurrounding and being spaced from said particulated material inlet tubeand being sealed to the bottom of said liquid entry chamber, arecirculated slurry entry chamber having a top, a bottom and a generallycircular inner peripheral wall, said particulated material inlet tubeand liquid outlet tube extending through said recirculated slurry entrychamber, said liquid outlet tube being sealed to the top of said slurryentry chamber, means for introducing slurry through said wall of saidslurry entry chamber, a recirculated slurry outlet tube, saidrecirculated slurry outlet tube surrounding and being spaced from saidliquid outlet tube and being sealed to said bottom of said slurry entrychamber, said slurry outlet tube extending at least to the bottom ofsaid liquid outlet tube and said particulated materials inlet tube,baffle means below said slurry outlet tube, a reservoir having wallsextending above the bottom of said slurry outlet tube, and means forrecirculating slurry from said reservoir to said means for introducingslurry.
 2. Apparatus in accordance with claim 1, wherein said liquidinlet means is a tangentially disposed tube.
 3. Apparatus in accordancewith claim 1, wherein said means for introducing recirculated slurry isdisposed generally tangentially with respect to the wall of said slurryentry chamber.
 4. Apparatus in accordance with claim 1, wherein saidparticulated material inlet tube, said liquid outlet tube and saidrecirculated slurry outlet tube are coaxial with respect to each other.5. Apparatus in accordance with claim 1, wherein said recirculatedslurry outlet tube extends substantially below said liquid outlet tubeand said particulated material inlet tube.
 6. Apparatus in accordancewith claim 1, wherein means are provided for applying liquid undersubstantial pressure to said liquid inlet means.